Combined cycle gas turbine with high temperature alloy, monolithic compressor rotor

Abstract

A high-temperature gas turbine includes a compressor, and a turbine coupled to the compressor, the turbine being capable of rotating at a high speed by a gas of firing temperature generated by a combustor. The compressor includes a combined type rotor shaft and blades of at least 15 stages which are implanted in the combined type rotor shaft. The compressor compresses air to a temperature of 400 DEG C. or above. The combined type rotor shaft is made of Ni-Cr-Mo-V low alloy steel having all bainitic microstructure whose composition consists, as analyzed in weight percent, of 0.15-0.40% C, 0.1% or less Si, 0.5% or less Mn, 1.5-2.5% Ni, 0.8-2.5% Cr, 0.8-2.0% Mo, 0.1-0.35% V and the balance substantially of Fe.

What is claimed is: 
     
       1. A combined cycle power plant including a gas turbine rotated by a combustion gas, a heat recovery steam generator for generating a steam from a heat energy of the combustion gas exhausted from said gas turbine, a steam turbine rotated by the steam, and a generator means driven by said gas turbine and said steam turbine to generate an electric power, wherein said gas turbine has a compressor for compressing air, the compressor has a monolithic rotor structure made of Ni--Cr--Mo--V low alloy steel with a bainite structure, the rotor shaft has blades of at least fifteen stages implanted therein, a compression ratio of the compressed air is 15-20, a temperature of the compressed air is not less than 400° C., a temperature of the combustion gas at a combustor outlet is not less than 1400° C., a temperature of the exhausted combustion gas is between 550° and 600° C., said steam turbine has a single casing structure which contains a combined high-pressure portion and a low-pressure portion rotor shaft, and a temperature of the steam is not less than 530° C. with at least one of a thermal efficiency is not less than 46%, and a specific power is not less than 600 KW/(kg/S).   
     
     
       2. A combined cycle power plant including a gas turbine rotated by a combustion gas, a heat recovery steam generator for generating a steam from a heat energy of the combustion gas exhausted from said gas turbine, a steam turbine rotated by the steam, and generator means driven by said gas turbine and said steam turbine to generate an electric power, wherein said gas turbine includes a compressor having a monolithic rotor shaft of made of Ni--Cr--Mo--V low alloy steel with a bainite structure, and blades of 15 to 20 stages which are implanted in the monolithic rotor shaft, air is compressed by said compressor with a compression ratio of 15-20, a temperature of the compressed gas is not less than 400° C., said turbine rotated by the combustion gas has moving blades of three stages, a temperature of the combustion gas at a combustor outlet is not less than 1400° C., and a temperature of the exhausted combustion gas at an inlet of said heat recovery steam heat recovery steam generator is between 550° and 600° C., a temperature of the exhausted combustion gas at an outlet of said heat recovery steam generator is not more than 130° C., said steam turbine has a single casing structure which contains a combined high-pressure portion and a low-pressure portion rotor shaft and blades implanted in said rotor shaft, a size of the blade of a last stage is not less than 30 inches at a blade portion thereof, and a temperature of the steam at a high-pressure inlet of said steam turbine is not less than 530° C., while a temperature of the steam at a low pressure outlet of said steam turbine is not more than 100° C.   
     
     
       3. A combined cycle power plant including a gas turbine rotated by a combustion gas, a heat recovery steam generator for generating a steam from a heat energy of the combustion gas exhausted from said gas turbine, a steam turbine rotated by the steam, and a generator means driven by said gas turbine and said steam turbine to generate an electric power, wherein said gas turbine has a compressor for compressing air, a compression ratio of the compressed air is 15-20, a temperature of the compressed air is not less than 400° C., a temperature of the combustion gas at the combustor outlet is not less than 1400° C., a temperature of the exhausted combustion gas is between 550° and 600° C. said steam turbine having a single casing structure which contains a combined high pressure portion and low pressure portion rotor shaft, and a temperature of the steam is not less than 530° C., with at least one of a thermal efficiency being not less than 45% and a specific power not less than 600 kW/(kg/S), said compressor has a monolithic rotor shaft and blades implanted in said rotor shaft, said rotor shaft is made of a Ni--Cr--Mo--V low alloy steel, a 50% fracture appearance transition temperature thereof is not more than 20° C. and a 10 5  hours of creep rupture strength under 475° C. is not less than 30 kg/mm 2 .   
     
     
       4. A combined cycle power plant including a gas turbine rotated by a combustion gas, a heat recovery steam generator for generating a steam from heat energy of the combustion gas exhausted from said gas turbine, a steam turbine rotated by the steam, and generator means driven by said gas turbine and said steam turbine to generate electric power, wherein said gas turbine includes a compressor for compressing air, a compression ratio of the compressed air is 15-20, a temperature of the compressed air is not less than 400° C., a temperature of the combustion gas at the combustor outlet is not less than 1400° C., a temperature of the exhausted combustion gas is between 550° and 600° C., said steam turbine has a single casing structure which contains a combined high pressure portion and low pressure portion rotor shaft, and a temperature of the steam is not less than 530° C., with at least one of a thermal efficiency being not less than 46% and a specific power not being less than 600 kW/(kg/S), said compressor has a monolithic rotor shaft and blades implanted in said rotor shaft, said rotor shaft is made of a Ni--Cr--Mo--V type low alloy steel having substantially an entire bainite microstructure which comprises, in weight percent, C of 0.15-0.40%, Si not more than 0.1%, Mn not more than 0.5%, Ni of 1.5-2.5%, Cr of 0.8-2.5%, Mo of 0.8-2.0%, V of 0.1-0.35% and the balance being substantially Fe.   
     
     
       5. A combined cycle power plant according to claim 4, wherein the Ni--Cr--Mo--V type low alloy steel further comprises, in weight percent, Co not more than 0.15%, W not more than 0.5%, B not more than 0.01%, Al not more than 0.1%, Ti not more than 0.3%, Zr not more than 0.1%, Hf not more than 0.1%, Ca not more than 0.01%, Mg not more than 0.01%, Y not more than 0.01%, and at least one rare-earth element not more than 0.01%. 
     
     
       6. A combined cycle power plant including a gas turbine rotated by a combustion gas, a heat recovery steam generator for generating a steam from a heat energy of the combustion gas exhausted from said gas turbine, a steam turbine rotated by the steam, and generator means driven by said gas turbine and said steam turbine to generate an electric power, wherein said gas turbine includes a compressor having a monolithic rotor structure and blades of 15-20 stages which are implanted in the monolithic rotor structure, air is compressed by said compressor with a compression ratio of 15-20, a temperature of the compressed gas is not less than 400° C., said turbine rotated by the combustion gas has moving blades of three stages, a temperature of the combustion gas at a combustor outlet is not less than 1400° C., a temperature of the exhausted combustion gas at an inlet of said heat recovery steam generator is between 550° and 600° C., a temperature of the exhausted combustion gas at an outlet of said heat recovery steam generator is not more than 130° C. said steam turbine has a single casing structure which contains a combined high pressure portion and low pressure portion rotor shaft, and blades implanted in said rotor shaft, a size of the blade of a last stage is not less than 30" at a blade portion thereof, and a temperature of the steam at a high-pressure inlet of said steam turbine is not less than 530° C., while a temperature of the steam at a low pressure outlet of said steam turbine is not more than 100°  C., said rotor shaft is made of Ni--Cr--Mo--V low alloy steel, a 50% fracture appearance transition temperature thereof is not more than 20° C. and a 10 5  hours of creep rupture strength under 475° C. is not less than 30 kg/mm 2 .   
     
     
       7. A combined cycle power plant including a gas turbine rotated by a combustion gas, a heat recovery steam generator for generating a steam from a heat energy of the combustion gas exhausted from said gas turbine, a steam turbine rotated by the steam, and generator means driven by said gas turbine and said steam turbine to generate an electric power, wherein said gas turbine includes a compressor having a monolithic rotor shaft and blades of 15-20 stages which are implanted in the monolithic rotor shaft, air is compressed by said compressor with a compression ratio of 15-20, a temperature of the compressed air is not less than 400° C., said turbine rotated by the combustion gas has moving blades of three stages, a temperature of the combustion gas at the combustor outlet is not less than 1400° C., and a temperature of the exhausted combustion gas at an inlet of said heat recovery steam generator is between 550° and 600° C., a temperature of the exhausted combustion gas at an outlet of said heat recovery steam generator is not more than 130° C., said steam turbine has a single casing structure which contains a combined high pressure portion and low pressure portion rotor shaft, and blades implanted in said rotor shaft, a size of the blade of a last stage is not less than 30" at a blade portion thereof, and a temperature of the steam at a high-pressure inlet of said steam turbine is not less than 530° C., while a temperature of the steam at a low pressure outlet of said steam turbine is not more than 100° C. said rotor shaft is made of Ni--Cr--Mo--V type low alloy steel having substantially entirely a bainite microstructure which comprises in weight percent, C of 0.15-0.40%, Si not more than 0.1%, Mn not more than 0.5%, Ni of 1.5-2.5%, Cr of 0.8-2.5%, Mo of 0.8-2.0%, V of 0.1-0.35% and the balance being substantially Fe.   
     
     
       8. A combined cycle power plant according to claim 7, wherein the Ni--Cr--Mo--V type low alloy steel further comprises, in weight percent, Co not more than 0.15%, W not more than 0.5%, B not more than 0.01%, Al not more than 0.1%, Ti not more than 0.3%, Zr not more than 0.1%, Hf not more than 0.1%, Ca not more than 0.01%, Mg not more than 0.01%, Y not more than 0.01%, and at least one rare-earth element not more than 0.01%.